1. Field of the Invention
The present invention relates to an apparatus for an a method of positioning and holding a photosensitive material to be used in a reproduction apparatus and particularly to an apparatus for and a method of positioning and holding a photosensitive material or the like having a sheet form to be placed on a photographing portion shaped like a table (referred to hereinafter as a photographing table) of a process camera.
2. Description of the Prior Art
It is well known that such a conventional process camera as shown in FIG. 1 has been used in graphic arts.
This vertical-type process camera comprises: a photographing table 2 provided in an upper portion of a frame body 1 and having a transparent plate 12; a lens mount 4 with a lens 5, provided under the photographing table 2 and movable vertically by means of bellows 3; an original table 7 having a pair of light sources 6, provided under the lens mount 4 in a vertically movable manner; and a transparent pressure plate 8 placed on the original table 7 for fixedly holding an original between the table 7 and the pressure plate 8. Thus, an image of the original held between the original table 7 and the pressure plate 8 is focused on a transparent plate 12 of the photographing table 2 through the lens 5 with a desired magnification and a photosensitive material 10 placed on the transparent plate 12 with its photosensitive surface directed downward is exposed so that the image is printed on the material 10.
The photographing table 2 comprises means 19 for positioning and holding the photosensitive material as shown in FIG. 2, as is well-known in the prior art.
More specifically, the positioning and holding means 19 comprises: a positioning mark sheet 21 having corner marks 22 for positioning along an optical axis of the camera the photosensitive material 10 placed on the transparent plate 12 of the photographing table 2; a light intercepting device 23 for spreading a light intercepting overlay sheet 25 over the mark sheet 21 under which the photosensitive material 10 is placed; and evacuation means 16 for evacuating the air between the transparent plate 12 and the overlay sheet 25 placed thereon through an evacuation channel 13 provided in peripheral portions of the transparent plate 12. The photosensitive material 10 is positioned between the transparent plate 12 and the mark sheet 21 by setting the corners of the photosensitive material 10 to the corner marks 22 while inserting the photosensitive material 10 therebetween. A sheet roller 26 of the light intercepting device 23 is rotated toward a front side directed to an operator, so as to spread the overlay sheet 25 on the photographing table 2. Then, the evacuation means 16 is operated to remove air trapped between the overlay sheet 25 and the transparent plate 12 of the table 2, whereby the photosensitive material 10 is retained in a desired position. The mark sheet 21 is, for example, of a flexible sheet member having one surface translucent for enabling the operator to check an image focused on the transparent plate 12. A rear end portion of the overlay sheet 25, opposite to the front side, is fixed on a rear edge portion of the table 2 by means of a presser plate 46 and fixing screws 47. A rear end portion of the mark sheet 21 may be fixed by means of an adhesive tape or the like as required.
It is to be noted, however, that the above mentioned positioning mark sheet 21 can be used only when the operator is allowed to visually check a positional relation between the corner marks 22 and the photosensitive material 10. In other words, the above mentioned mark sheet 21 can be used only in the case of a photosensitive material permitted to be used under safety light, but cannot be used in the case of a photosensitive material permitted to be used only in utter darkness, such as a panchromatic film.
Accordingly, in the latter case, a positioning method called a register pin system, for example, is used conventionally. In the register pin system, a pin bar 28 having register pins 29 is fixed in a desired position on the transparent plate 12 by using an adhesive tape or the like, as shown by broken lines in FIG. 2, and pin holes corresponding to the register pins 29 are provided in the photosensitive material 10, so that the operator can manually position the photosensitive material with precision even in utter darkness by fitting the register pins 29 into the pin holes.
However, in the register pin system, it is necessary as a preparatory step to form pin holes in the photosensitive material after the pin bar 28 is fixed on the transparent plate 12 and it is also necessary to change the position of the pin bar 28 each time the size of a photosensitive material to be used is changed. In addition, it is necessary to completely remove the remaining material of the adhesive tape or the like torn off from the transparent plate 12 each time, thereby to avoid considerable decrease of picture quality. Thus, the register pin system requires troublesome preparation and aftertreatment, causing efficiency of work to be lowered. Furthermore, for such work in utter darkness, the mark sheet is unsuitable or rather a nuisance.